Self-contained portable apparatus for administration of a drug solution

ABSTRACT

A self-contained portable apparatus for administration of a drug solution includes a housing having an enclosure for receiving a flexible pouch containing a drug solution, the output of which is connectable to a conduit for delivering the drug solution to a recipient. A pressurization system is arranged for providing a constant and controllable gas pressure to the housing in order to obtain a controllable delivery of the drug solution. The pressurization system includes a pressure source for delivering positive pressure gas; a pressure accumulation tank connected to the source and the second chamber; a one-way valve arranged between the pressure source and the pressure accumulation tank; and a mechanical pressure regulator arranged between the pressure accumulation tank and the housing. Hereby, an extremely stable and well controllable output pressure and output flow is obtainable.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of copending application Ser. No.12/285,700 filed on Oct. 10, 2008, which claims the benefit of U.S.Provisional Application No. 60/960,770 filed on Oct. 12, 2007 and toPatent Application No. 07118365.1 filed in the European PatentCommunity, on Oct. 12, 2007. The entire contents of all of the aboveapplications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a self-contained portable apparatus foradministration of a drug solution, and in particular an apparatus whichis usable for administration of liquid medicaments to a patient, e.g.for use in post-operative pain relief. The apparatus is arranged toprovide a very uniform and controllable flow rate.

BACKGROUND OF THE INVENTION

The administration of medical liquids is largely carried out bygravity-induced hydrostatic pressure infusion of the liquid from abottle or other container suspended above the recipient an acceptabledistance. The liquid empties by gravity at a rate of flow which can beregulated by what is known as a drop-by-drop device which reduces therate of flow by restriction or compression of the flexible tube carryingthe liquid which is to be injected. Although this equipment is used inhospitals, it is however bulky, difficult to move, clumsy and slow toset up. Further, the flow rate is not easily controlled since variationsin relative positions of the receiving portion of the patient and thedispensing bottle may occur with time as the patient or bottle may beshifted about.

Moreover, previously available pressure-assisted administration devicesare often quite complicated and expensive, and also often lackportability. Further, these known apparatuses are often unable toprovide, as well as continuously maintain for a long time, a desiredflow rate.

Still further, most known administration devices require that the drugsolution is discharged from its original container, i.e. from theprepackaged, disposable, standard medical containers, and into aadministration reservoir of the administration apparatus. This isnormally a rather tedious and cumbersome task, and also invokes a riskfor contamination, since the solution must pass through additionalhandling steps in the preparation and transfer process, prior to beingintroduced to a patient.

In many situations, a patient may also require a very slow andcontinuous introduction of medicament liquid into the patient's system,such as a few milliliters per hour for several hours, or sometimes evena day or more. It is therefore very important that these medicamentliquid or pharmaceutical solution doses be administered with a highlyaccurate introduction rate (flow rate), which is maintained very stableduring the entire process.

To this end, many of today's administration apparatuses comprisescomplex electronic systems. For example, such systems may includecomplex valve arrangement by which the fluid is introduced into thechamber and withdrawn there from, and controlled by a electroniccircuitry which includes pressure sensors and logic circuitry whichcontrols fluid pumps which move the liquid. While relatively compact andaccurate, these systems are also highly complex, expensive and requiresa great deal of electrical power to operate. Further, these apparatusesare solely intended for multi-time use, which necessitates cumbersomeand tedious cleaning and sterilization of the apparatuses before re-use,and also invokes a risk for contamination of the patient.

Further, it is known from the prior art to produce portable andmechanical administration devices. For example, U.S. Pat. No. 3,460,277discloses a self-contained portable administration apparatus using CO2cartridges to obtain a relatively precisely regulated gas flow todisplace a medical arranged in a pressure collapsible container. To thisend, the pump device comprises a casing comprising a collapsible bladderholding the fluid to be driven (the medical liquid) and a secondinflatable bladder to be filled with a driving fluid, whereby expansionof the second bladder causes the medical liquid to be controllablyexpelled. However, this device is still relatively complicated andexpensive to produce, and there is also a problem of obtaining asufficiently continuously stable and controllable pressure acting of thepressure collapsible container holding the medical liquid. Similarproblems are also encountered in the apparatus disclosed in U.S. Pat.No. 5,954,696 and U.S. Pat. No. 4,673,392, which are both related tosimilar types of administration apparatuses.

Consequently, there is still a need for administration apparatuses whichare both capable of providing a sufficiently stable and controllableflow rate, and at the same time are safe and inexpensive to produce anduse.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide aself-contained, portable apparatus for administration of a drugsolution, which at least alleviates the above-discussed problems of theprior art.

This object is achieved with an administration apparatus according tothe appended claims.

According to the invention, there is provided a self-contained portableapparatus for administration of a drug solution, said apparatuscomprising:

-   -   a housing having an enclosure for receiving a flexible pouch        containing a drug solution, wherein said enclosure has a first        chamber within said pouch and a second chamber arranged outside        said pouch, the chambers being arranged in a        pressure-transmitting relation within said enclosure;    -   an output from said first chamber connectable to a conduit for        delivering said drug solution to a recipient; and    -   a pressurization system for providing a constant and        controllable gas pressure to said second chamber, wherein a        controllable pressure is obtained in said first chamber for a        controllable delivery of the drug solution.

Further, the pressurization system comprises:

-   -   a pressure source for delivering positive pressure gas;    -   a pressure accumulation tank connected to said source and to        said second chamber, arranged to provide a positive pressure        reservoir;    -   a one-way valve arranged between said pressure source and said        pressure accumulation tank, enabling gas to flow solely in the        direction from the pressure source to the pressure accumulation        tank; and    -   a mechanical pressure regulator arranged between said pressure        accumulation tank and said second chamber.

The administration apparatus according to the invention is relativelysimple, and can be produced relatively cost-effectively. Hereby, it ispossible to provide this administration apparatus as a disposable, forone-time use, and the like, which makes it very safe and secure from acontamination point of view. Further, the inventive pressurizationsystem, involving inter alia an accumulation tank, enables a multitudeof various pressure sources to be used, and at the same time theprovision of a very stable and controllable system, where the pressureacting on the flexible pouch containing the drug solution in theenclosure of the housing is extremely stable over time, and essentiallyconstant even when the flexible pouch is full or nearly empty.Accordingly, the present invention provides a very stable and constantoutgoing pressure for the drug solution. Further, the pressure in thepressurization system may always be kept below 3 bar, which reduces thesafety risks of the system, and also reduces the safety requirements ofthe system. The only exception to this is, possibly, the pressuresource, where higher pressures may provided. However, in that case theaccumulation tank functions as a buffer to the rest of the system,thereby ensuring adequate safety of the overall system.

The present administration apparatus may be equipped with any type offlexible pouch for holding the drug solution, such as prepackaged,disposable, standard medical containers of flexible materials.

The invention is particularly useful for administration of e.g. painrelieving agents such as anesthetics during post-operation treatment ofa patient at a low administration rate during a prolonged time. Forexample, the apparatus may be arranged to provide an output flow rate ofthe drug solution in the range 1-200 ml/h, and preferably in the range1-20 ml/h, and most preferably in the range 4-12 ml/h. Further, theapparatus may be arranged to provide an essentially constant outputpressure and output flow rate for at least 1 hour, and preferably for atleast 12 hours, and most preferably for at least 24 hours.

The administration apparatus may be used for any type of drug solution,such as liquid medicaments for post-surgery pain relief, such assolutions of ropivakain and other local anesthetics, for instance Narop®and Naropin®, both produced by AstraZeneca. However, the administrationapparatus may also be used to deliver intravenous fluids and solutionsfor a wide variety of medical therapies including chemotherapy,antiviral and antibiotic therapy, and also include intravenousintroduction of saline solutions, glucose solutions and various othersolutions comprising pharmaceuticals. In e.g. post-surgery use ofanesthesia, the drug solution may be administered through a catheterafter surgery and after closing of the surgical incision.

The present invention is an entirely mechanical construction, which doesnot need any electronics or the like for its operation. Further, theapparatus may be made very compact, and thereby portable andself-contained. Still further, the drug solution is at all timesmaintained separated from the pressurization system, which makes theapparatus very safe, and significantly reduces the risk forcontamination of the drug solution, and also makes it possible to useless expensive materials in the pressurization system, since thesematerials need not be compatible for the drug solution, etc.

Due to the extremely accurate pressure provided by the pressurizationsystem and acting on the flexible pouch holding the drug solution, noflow regulation or the like are in principle needed in the conduittransferring the drug solution to the patient. However, in most casesflow control means may still be advantageous in the conduit system. Forexample, it may be advantageous to provide a branched conduit system,with one branch providing a continuous drug administration to thepatient, and a second branch with a liquid reservoir providing thepossibility of bolus doses. Typically, the continuous drugadministration can e.g. be 1-20 ml/h, and preferably 2-14 ml/h, and thebatch-wise (bolus) dosages can be e.g. 5-30 ml extra every 1-6 hour.Further, since the pressurization system provides an essentiallyconstant pressure on the flexible pouch holding the drug solution, italso becomes possible to control the output liquid flow from theapparatus with great accuracy, and by relatively simple means.

The pressure source is preferably a hand-operated pump. Hereby, the pumpmay be used to manually fill the accumulation tank with an adequatepressure before starting the drug administration, and may also be usedduring use, for increasing the pressure in the accumulation tank. Mostpreferably, the pump comprises an air compression cup which is slideablyarranged over the pressure accumulation tank. Hereby, a very compactproduct is obtainable. However, other alternative pressure sources mayalso be used for filling the accumulation tank, such as a liquefied gascontainer, and preferably a liquefied CO₂ container, or a container withpressurized air.

The one-way valve ensures that pressurized gas is only transferred inthe direction from the pressure source to the accumulation tank, and notin the reverse direction. This makes it possible only to activate thepressure source temporarily or intermittently, such as only initially,before starting the drug administration to the patient, or only when thepressure in the accumulation tank becomes lower than a predeterminedthreshold value.

The mechanical pressure regulator guarantees that a stable and constantgas pressure is provided from the accumulation tank to the secondchamber, and that the pressure in the enclosure is automaticallyadjusted during the emptying of the flexible pouch holding the drugsolution. Such mechanical pressure regulators are per se previouslyknown.

The apparatus is preferably arranged to provide an essentially constantoutput pressure for the drug solution, said output pressure preferablybeing in the range 0.1-1.0 bar, and most preferably 0.3-0.6 bar.

The pressure accumulation tank is preferably capable of accumulating apressure exceeding 1 bar, and preferably exceeding 2 bar. Further, as asafety measure, the pressure accumulation tank is preferably providedwith a high-pressure relief valve, arranged to release pressure from theaccumulation tank if the pressure exceeds a certain threshold limit,such as a threshold limit of 3 bar. Similarly, the enclosure in thehousing may be provided with a high-pressure relief valve, arranged torelease pressure from enclosure if the pressure exceeds a certainthreshold limit.

The second chamber is preferably arranged as an expandable bladder, saidbladder being arranged adjacent to said flexible pouch within saidenclosure. However, alternatively, the second chamber may be provided inthe enclosure by means of a flexible membrane arranged between acompartment holding the first chamber and a compartment forming thesecond chamber. Still further, the second chamber may be the entirety ofthe enclosure being exteriorly from the flexible pouch holding the drugsolution, whereby the gas acts directly on the flexible pouch.

The housing is preferably made of relatively rigid material, andpreferably a rigid plastic material.

A manometer is preferably arranged on the pressure accumulation tank,for providing an indication of the current pressure in said tank. Thiscan be used for monitoring the present pressure of the tank, and alsofor monitoring the operation of the drug administration.

Further, the housing is preferably further provided with a manuallycontrollable valve for releasing the pressure of the second chamber.Hereby, the pressure of the second chamber can at all times be releasedto atmosphere pressure, for e.g. for exchange of the flexible pouch orother maintenance operations.

Still further, the mechanical pressure regulator is preferably arrangedbetween said pressure accumulation tank and said second chamber iscontrollable to provide different pressures to the second chamber.Hereby, the pressure in the second chamber becomes controllable, and canbe set for different pressure levels by means of controlling thepressure regulator. This may e.g. be used for set-up of theadministration apparatus for various types of use, or for controllingthe pressure of the second chamber during use, for controlling theoutput flow of the drug solution.

According to another aspect of the invention, there is provided a methodfor administration of a drug solution, comprising the steps:

-   -   providing a flexible pouch containing a drug solution in a        housing; and    -   providing a pressure in a second chamber arranged outside said        pouch within said housing, said pressure thereby acting on the        flexible pouch for delivering said drug solution to a recipient;    -   wherein said pressure in the second chamber is provided by the        additional steps:    -   providing a positive pressure from a pressure source;    -   forwarding at least part of said pressure from the pressure        source to a pressure accumulation tank connected to said source        through in a non-returnable way; and    -   forwarding at least part of said pressure from the pressure        accumulation tank to the second chamber through a mechanical        pressure regulator arranged between said pressure accumulation        tank and said second chamber.

By means of this aspect of the invention, similar advantages areobtainable and corresponding preferred embodiments are feasible asdiscussed above in relation to the corresponding first aspect of theinvention.

These and other aspects of the invention will be apparent from andelicidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

For exemplifying purposes, the invention will be described in closerdetail in the following with reference to embodiments thereofillustrated in the attached drawings, wherein:

FIG. 1 is a schematic view of the principal construction of anadministration apparatus according to a first embodiment of the presentinvention;

FIG. 2 shows a second embodiment of an administration apparatusaccording to the present invention;

FIG. 3 is an exploded view of the administration apparatus of FIG. 2;

FIG. 4 is a diagram illustrating the deviation in the average outputflow over the entire operation cycle for the present invention and anumber of comparative examples; and

FIG. 5 is a diagram illustrating the measured pressure in the secondchamber and the accumulation tank, as well as the resulting flow for thesecond chamber, of the administration apparatus of FIGS. 2 and 3 duringoperation.

DESCRIPTION OF PREFERRED EMBODIMENTS

The invention will now be discussed in more detail by means ofembodiments. Unless otherwise is specifically mentioned, the differentfeatures are mutually exchangeable between the embodiments, and further,the same reference numerals are used to denominate similar orcorresponding parts throughout the drawings and the specification.

An administration apparatus for administration of a drug solutionaccording to a basic first embodiment, as illustrated in FIG. 1,comprises a housing 1 having an enclosure 2 for receiving a flexiblepouch (not shown) containing a drug solution. In this context “flexible”indicates that the pouch forms a pressure-collapsible container, wherebythe liquid arranged in the pouch is releasable by compression operatingthereon. The enclosure forms a first chamber within said pouch and asecond chamber arranged outside said pouch, wherein the chambers arearranged in a pressure-transmitting relation within said enclosure.Hereby, the pressure provided in the second chamber is transferred tothe first chamber, and consequently the pressure provided in the secondchamber is essentially equal to the pressure obtained in the drugsolution contained in the flexible pouch.

Thus, the housing forms separate chambers for the driving gas and thedriven drug solution, formed by separate and abutting collapsiblecontainers, respectively, having a large common interface. The housingforms a rigid container or frame. Part of the housing is formed by a lidor removable wall section, to permit insertion of a new medicalcontainer of drug solution, and removal of an emptied container.

The housing is preferably made at least partly of a transparent plasticmaterial in order to permit immediate visual monitoring of the conditionof the inner bag. Further, the housing may be injection molded, pressureformed, or the like.

An output from the first chamber is connectable to a conduit (not shown)for delivering said drug solution to a recipient, and in particular to apatient. For example, the conduit may comprise tubing leading from thefirst chamber, a valve for opening and closing the conduit and acatheter for introduction of the drug solution into the patient. Forexample, it may be advantageous to provide a branched conduit system,with one branch providing a continuous drug administration to thepatient, and a second branch with a reservoir of drug solution providingthe possibility of bolus doses. Such conduits are per se known in theart, and will not be discussed in any detail in this application.

Further, the administration apparatus comprises a pressurization systemfor providing a constant and controllable gas pressure to said secondchamber. The pressurization system comprises a pressure source 3 fordelivering positive pressure gas. In this embodiment, the pressuresource is a hand-actuated pump, but other pressure sources, such as aliquid gas cartridge, are also feasible. A pressurized driving fluidsupply meeting these requirements is e.g. a cartridge in which is storedliquefied CO₂, fluorocarbons or hydrocarbons contained under pressuresrequired to maintain liquid-gas equilibrium, or gases such as N₂ or airunder high pressure. Another alternative would be to use an externalpressure source, which could then be used for loading the accumulationtank before use of the apparatus, and possible even for subsequentreloading during use.

The pressure source 3 is connected to a pressure accumulation tank 5,which provides a positive pressure reservoir. The accumulation tank ispreferably arranged to be pressurized up to a positive pressure duringinitialization of the administration apparatus, e.g. up to 1-2 bar, oreven up to 3 bar. However, it is in many cases an advantage to have anaccumulation tank having a pressure below 3 bar connected to theadministration system, since this provides lower safety risks, andtherefore requires less safety requirements. In many applications, theinitial loading of the accumulation tank will be sufficient for thewhole administration process. However, it is also possible to reload theaccumulation tank during operation. Between the pressure source 3 andthe accumulation tank 5 a one-way valve 4 is provided, which allows gasto flow from the pressure source to the accumulation tank, but preventsgas from flowing in the opposite direction.

The accumulation tank is connected to the second chamber within theenclosure 2 via a mechanical pressure regulator 6, arranged to controlthe pressure within the second chamber to a predetermined pressurelevel, said pressure level being lower than the pressure of theaccumulation tank. The pressure regulator is arranged to mechanicallyand automatically control the output pressure to a predetermined value.Optionally, this predetermined value may be manually controllable, inorder to enable adjustment of the predetermined value during operation,or for adjustment between various types of operations. Thus, thepressure regulator 6 reduces the pressure of the driving fluid from alever p₁ to a level p₂, and the latter may be varied within limits byadjustment of a regulator control (not shown). Normally, p₂ is much lessthan p₁. The regulator control for adjustment of the output pressure maye.g. adjust a spring tension in the regulator. Several pressureregulators, both of spring and diaphragm type, are per se known in theart, and are commercially available.

The administration apparatus is preferably arranged as a self-containedand portable device. Even though this goal may be achieved by means ofthe apparatus discussed above in respect of FIG. 1, the embodimentillustrated in FIGS. 2 and 3 illustrate an even more compact, portableand self-contained apparatus.

The housing 1 receives a flexible pouch 10 for holding the drugsolution, such as prepackaged, disposable, standard medical containersof flexible materials, said pouch forming the first chamber. Inpractice, any one of a number of standard drug solution containers maybe used with the administration apparatus of the present invention, butsolution containers in the range 50-500 ml are preferred, and mostpreferably in the rage 100-300 ml.

An inflatable bladder 11 is wrapped around the flexible pouch 10 andalso arranged within the housing 1, thereby forming the second chamber.

The housing 1 forms a receptacle with an openable lid 13. Afterinsertion of the flexible pouch 10, the lid 13 is closed. Preferably,the lid is arranged with a snap lock, such as flexible locking arms 15.However, the lid may be attached to the housing bottom by any of avariety of conventional mechanical fasteners, such as push-pins, screws,snap-fit posts and detents, and the like.

Further, the lid is preferably arranged with an inner wall 14 to beinserted into the housing 1. Hereby, the lid stabilizes the housing, andthereby aids in the resistance against the positive pressure building upwithin the housing during operation. Still further, the lid ispreferably arranged with an output opening 16, which is connectable to aconduit (not shown) for delivering said drug solution to a recipient,and in particular to a patient. The conduit for delivering the drugsolution to the patient may comprise a needle or other device, such as acatheter, for administering fluids, and tubing connecting the outputopening 16 to the needle or catheter end. The conduit may also comprisefilters, such as air elimination filters and particle eliminationfilters, bisections for enabling both bolus doses and continuousadministration, flow controlling resistive lumen or orifices etc. Suchconduits are per se known in the art.

The output opening may be connected to an internal needle or spike,which penetrates a membrane of the flexible pouch during insertion ofthe pouch into the housing and closing of the lid. Hereby, fluidconnection between the flexible pouch and the administration conduit isobtained automatically during arrangement of the flexible pouch withinthe housing. The drug spike may be of the type which is per se wellknown in the art. However, other type of access means are feasible. Forexample, the output opening may simply be an opening, through which aconnection part of the flexible pouch is accessible.

The pressurization system is arranged on the side of the housing, andformed as integrated parts on or within the housing 1. In thisembodiment, the accumulation tank 5 is arranged at the side of thehousing, and essentially extending over the whole length of the housing.A gap is formed between the accumulation tank and the housing in one endof the tank, so that the accumulation tank is only connected to thehousing in one end. Further, the accumulation tank has a uniformcross-section at least in the part not connected to the housing, andpreferably an essentially circular cross-section. Further, an openingwith a non-return valve 4 is arranged at the end side of thenon-connected end of the tank. A hand-actuated pump, functioning as apressure source 3, is arranged outside the accumulation tank 5, and inparticular outside the part of the tank which is not connected to thehousing, and is displaceable or slideable in the length direction of thetank. Hereby, the pump forms a cylinder, or a compression cup, with aninternal cross-section which generally corresponds to the externalcross-section of the corresponding part of the accumulation tank,whereby a relatively tight seal is formed between the pump and theaccumulation tank. However, other alternative pressure sources may alsobe used for filling the accumulation tank, such as a liquefied gascontainer, and preferably a liquefied CO₂ container or a container ofpressurized air.

The accumulation tank 5 is connected to the inflatable bladder 11 withinthe enclosure 2 via a mechanical pressure regulator 6, arranged tocontrol the pressure within the inflatable bladder to a predeterminedpressure level, lower than the pressure of the accumulation tank.

During operation, the pump 3 is displaced up and down on theaccumulation tank, whereby air is forced through the one-way valve 4into the accumulation tank 5, whereby a pressure is built up in thetank. This positive pressure is gradually released to the inflatablebladder 11 through the exact control of the regulator 6, whereby a veryexact and constant pressure is applied on the liquid medicine arrangedin the flexible pouch 10.

The volume of the pressure accumulation tank as well as the initialpressure as provided by the pressure source are preferably selected independence of the total volume of the drug to be administered, and thedesired output pressure in the second chamber of the housing.Preferably, the volume of the accumulation tank is relatively small, inorder to reduce the overall size of the apparatus. For example, it ispreferred that the accumulation tank has an internal volume V_(acc) thatis less than the internal volume V_(pouch) of the pouch (first chamber)holding the drug solution, and preferably less than 70% of this volume,and most preferably less than 50% of this volume. Further, it ispreferred that the pressure source is operable to provide an initialpressure to the accumulation tank that is sufficient to completely emptythe pouch. Accordingly, the pressure source is preferably operable toprovide a pressure P_(acc,initial) to the accumulation tank thatfulfills the following condition:

P _(acc,initial) ≧P _(reg)*(V _(acc) +V _(pouch))/V _(acc)

where P_(reg) is the regulated pressure of the second chamber, acting onthe first chamber (i.e. the pouch), V_(pouch) is the volume of thepouch, i.e. the volume of the drug to be administered, and V_(acc) isthe volume of the accumulation tank.

The administration apparatus is particularly useful for administrationof e.g. pain relieving agents such as anesthetics during post-operationtreatment of a patient at a low administration rate during a prolongedtime. For example, the apparatus may be arranged to provide an outputflow rate of the drug solution in the range 1-200 ml/h, and preferablyin the range 1-20 ml/h, and most preferably in the range 4-12 ml/h.Further, the apparatus may be arranged to provide an essentiallyconstant output pressure and output flow rate for at least 1 hour, andpreferably for at least 12 hours, and most preferably for at least 24hours. Further, an essentially constant output pressure for the drugsolution can hereby be provided, e.g. in the range 0.1-1.0 bar, and mostpreferably 0.3-0.6 bar.

Further, as a safety measure, the pressure accumulation tank ispreferably provided with a high-pressure relief valve 12, arranged torelease pressure from the accumulation tank if the pressure exceeds acertain threshold limit. Similarly, the enclosure in the housing may beprovided with a high-pressure relief valve, arranged to release pressurefrom enclosure if the pressure exceeds a certain threshold limit. Thehigh-pressure relief valve may also be arranged to provide an alarmsound or the like, such as a whistle tone, when it is activated.Manometers (e.g. 17 in FIG. 3) and the like may also be provided toindicate the present pressure in e.g. the accumulation tank or thesecond chamber during use. Such a manometer may also be used formonitoring the flow of drug solution out of the administrationapparatus, and/or as a measure of the amount of drug solution remainingin the flexible pouch.

Experimental Results

An administration apparatus as discussed above with reference to FIG. 2was used for experimental measurements. The output of the apparatus wasconnected to a flow regulator, which allowed a flow of 4 ml/h at anoverpressure of 0.4 bar. The output of the flow regulator was forwardedthrough a catheter, and the drug administered through the catheter wascollected and weighed. Further, manometers were used to measure thepressure in the first and second chamber of the housing.

For the experiments, a pouch holding a drug solution was arranged in thehousing, and administered by means of the administration apparatus. Theweight of the administered drug was continuously measured, together withthe pressure in the first and second chamber, until the nominal volumewas delivered from the pouch.

The result of this measurement is presented in the diagram of FIG. 5. Inthis diagram, the x-axis represents the time, extending from close to 0minutes to about 1500 minutes (25 hours), which is the time when thenominal volume was delivered from the pouch. On the y-axis, flow andpressure are represented. FIG. 5 illustrates the pressure in the secondchamber (dashed line) and the corresponding pressure in the accumulationtank (full line). Further, the resulting flow rate (dash dotted line) isillustrated. Accordingly, it is clearly discernible how the pressure inthe accumulation tank constantly falls from a relatively high pressurelevel to a pressure level only slightly above the pressure in the secondchamber, whereas the pressure in the second chamber, as well as theoutput flow rate, remain essentially constant and extremely stableduring the entire process.

Accordingly, the new drug administration apparatus exhibits a verystable output flow and output pressure, with a very limited variationover the entire process. As a comparison, a similar evaluation was madefor some commercially available drug administration apparatuses. Theresult of this evaluation is presented in the diagram of FIG. 4, inwhich the x-axis represents the relative amount of delivered drug,extending from 0% of the nominal value to 100% of the nominal volume.The y-axis indicates the deviation in percent at each time from theaverage flow. The evaluated administration devices were:

-   -   the administration apparatus according to the present invention.        (Dotted line);    -   comparative example I is an elastomeric balloon infusion system        with a nominal flow rate of 5 ml/h and a nominal volume of        240 ml. (Dashed line);    -   comparative example II is an elastomeric balloon infusion system        with a nominal flow rate of 5 ml/h and a nominal volume of        270 ml. (Full line);    -   comparative example III is a spring-operated infusion system        with a nominal flow rate of 4 ml/h and a maximum volume of        100 ml. (Dash dotted line); and    -   comparative example IV is an elastomeric balloon infusion system        with a nominal flow rate of 5 ml/h and a nominal volume of        275 ml. (Dash dotted line with double dots).

From the evaluation in FIG. 4, it is clearly noticeable that thecommercially available comparative examples I-IV all have much higherdeviations from the average flow rate during the process, and typicallywith a flow rate much above the average in the initial phase, when thechamber or pouch containing the drug solution is full, and with a flowrate much below average during the final phase, when the chamber/pouchis almost empty.

CONCLUSION

The drug administration apparatus of the present invention is aself-contained and portable apparatus, which, by reason of itsconvenience and simplicity of use, is well suited for a large variety ofdrug administration applications. The apparatus according to theinvention does not require any skill in use. It is easily and quicklypositioned. It can easily be moved and carried by the injured person orby the medical staff, and thereby causes no hindrance in handling andtransporting the patient. The simplicity of the constituent parts alsoguarantees a low manufacturing cost. Consequently, the apparatus canalso be made as a disposable, for use on only one patient. This, incombination with the separation of the pressurization system and thedrug and the fact that the drug is allowed to remain in its pre-packedcontainer, provides an extremely clean and secure drug administration,which minimizes the risk for contamination for the patient.

At the same time, the present invention provides, in a medical liquidadministration system, means for providing an adequately regulatedoutput pressure from the pressurization system, acting on the drug to beadministered, to selectively, reliably, and accurately displace the drugand cause the drug also to flow at a substantially constant flow rate.Hereby, the drug can be allowed to remain in a pre-packed flexible bagduring the whole administration process, and with the pressurizationsystem fluidly separated from the drug, and is also usable with standardmanufacturers' drug solution containers to provide efficient, accurateand low cost administration.

The administration apparatus of the illustrated embodiment uses acompact, reliable and cost effective pressure source, such as amechanical, hand-operated pump. The administration apparatus isparticularly reliable and cost-effective since it includes neitherelectronic components to control or monitor operation, nor batteries asa primary power source. Because of its compact construction theadministration apparatus according to the invention is able to functioneven after having been dropped, and because of its lack of electronics,the pump is able to operate even if it comes into contact with water orthe like from the outside. Still further, the pumping means can be madevery compact, as a cup like member arranged around the accumulationtank. Still further, the present administration apparatus allows easyexchange of the pouch holding the drug.

Specific embodiments of the invention have now been described. However,several alternatives are possible, as would be apparent for someoneskilled in the art. For example, the second chamber, providing theexternal pressure on the first chamber, i.e. the pouch, within thehousing may be provided in various ways. One alternative is to arrangethe second chamber within a second pouch, or a flexible bag, asdiscussed above. More than one pouch forming the second chamber may lsobe provided, such as two flexible bags arranged on each side of thepouch holding the drug solution. Another alternative to make the housingair-tight, whereby the second chamber may be the part of the housingexternally from the pouch holding the drug solution.

Further, even though an important application of the presentadministration apparatus is to administer a drug solution, such asanesthetics, directly to a patient, other applications are alsofeasible, such as administration of a drug solution to another apparatusor the like. Further, the administration apparatus may be used for alarge variety of different drugs, such as for use in open wounds, e.g.for post-surgical treatment, for use during surgery, for intravenoususe, for epidural administration, for cancer treatment, neurosurgery,etc. In general, the present administration apparatus is useable for allapplications where a pressure is needed for forwarding the drug from thedrug container to the place where it is needed.

Still further, the apparatus may be arranged to provide a predeterminedoutput pressure and output flow from the first chamber. Alternatively,the output pressure may be controllable, e.g. by the provision of acontrollable pressure regulator between the accumulation tank and thesecond chamber. Alternatively or additionally, a flow regulator orcontrollable flow restrictor, such as capillaries of various sizes, maybe used for controlling the output flow from the first chamber.

Such and other obvious modifications must be considered to be within thescope of the present invention, as it is defined by the appended claims.

1. A self-contained portable apparatus for administration of a drugsolution, said apparatus comprising: a housing having an enclosure forreceiving a flexible pouch containing a drug solution, wherein saidenclosure has a first chamber within said pouch and a second chamberarranged outside said pouch, the chambers being arranged in apressure-transmitting relation within said enclosure; an output fromsaid first chamber connectable to a conduit for delivering said drugsolution to a recipient; and a pressurization system for providing aconstant and controllable gas pressure to said second chamber, wherein acontrollable pressure is obtained in said first chamber for acontrollable delivery of the drug solution, wherein said pressurizationsystem comprises: a pressure source for delivering positive pressuregas; a pressure accumulation tank connected to said source and to saidsecond chamber, arranged to provide a positive pressure reservoir; aone-way valve arranged between said pressure source and said pressureaccumulation tank, enabling gas to flow solely in the direction from thepressure source to the pressure accumulation tank; and a mechanicalpressure regulator arranged between said pressure accumulation tank andsaid second chamber.
 2. The apparatus of claim 1, wherein the pressuresource comprises a hand-operated pump.
 3. The apparatus of claim 1,wherein the pump comprises an air compression cup which is slideablyarranged over the pressure accumulation tank.
 4. The apparatus of claim1, wherein the pressure source comprises a liquefied gas container. 5.The apparatus of claim 4, wherein the liquefied gas container is aliquefied CO₂ container.
 6. The apparatus of claim 1, wherein the drugsolution is an anesthetic.
 7. The apparatus of claim 1, wherein it isarranged to provide an output flow rate of the drug solution in therange 1-200 ml/h.
 8. The apparatus of claim 7, wherein it is arranged toprovide an output flow rate of the drug solution in the range 1-20 ml/h.9. The apparatus of claim 8, wherein it is arranged to provide an outputflow rate of the drug solution in the range 4-12 ml/h.
 10. The apparatusof claim 1, wherein it is arranged to provide an essentially constantoutput flow rate for at least 1 hour.
 11. The apparatus of claim 10,wherein it is arranged to provide an essentially constant output flowrate for at least 12 hours.
 12. The apparatus of claim 11, wherein it isarranged to provide an essentially constant output flow rate for atleast 24 hours.
 13. The apparatus of claim 1, wherein it is arranged toprovide an essentially constant output pressure for the drug solution.14. The apparatus of claim 13, wherein said essentially constant outputpressure is in the range 0.1-1.0 bar.
 15. The apparatus of claim 14,wherein said essentially constant output pressure is in the range0.3-0.6 bar
 16. The apparatus of claim 1, wherein the pressureaccumulation tank is capable of accumulating a pressure exceeding 1 bar.17. The apparatus of claim 16, wherein the pressure accumulation tank iscapable of accumulating a pressure exceeding 2 bar.
 18. The apparatus ofclaim 1, wherein the pressure accumulation tank is provided with ahigh-pressure relief valve, arranged to release pressure from theaccumulation tank if the pressure exceeds a certain threshold limit. 19.The apparatus of claim 18, wherein the high-pressure relief valve isarranged to maintain a pressure below about 3 bar in the accumulationtank.
 20. The apparatus of claim 1, wherein the enclosure in the housingis provided with a high-pressure relief valve, arranged to releasepressure from enclosure if the pressure exceeds a certain thresholdlimit.
 21. The apparatus of claim 1, wherein said second chamber isprovided in an expandable bladder, said bladder being arranged adjacentto said flexible pouch within said enclosure.
 22. The apparatus of claim1, wherein the housing is made of relatively rigid material.
 23. Theapparatus of claim 1, wherein the housing is made of relatively rigidplastic material.
 24. The apparatus of claim 1, wherein the apparatusforms a disposable product for one time use.
 25. The apparatus of claim1, wherein the enclosure of the housing is arranged to receive a pouchof drug solution which is a standard disposable pre-filled medicamentcontainer.
 26. The apparatus of claim 1, wherein a manometer is arrangedon the pressure accumulation tank, for providing an indication of thecurrent pressure in said tank.
 27. The apparatus of claim 1, wherein thehousing is further provided with a manually controllable valve forreleasing the pressure of the second chamber.
 28. The apparatus of claim1, wherein the mechanical pressure regulator arranged between saidpressure accumulation tank and said second chamber is controllable toprovide different pressures to the second chamber.
 29. A method foradministration of a drug solution, comprising the steps: providing aflexible pouch containing a drug solution in a housing; and providing apressure in a second chamber arranged outside said pouch within saidhousing, said pressure thereby acting on the flexible pouch fordelivering said drug solution to a recipient; wherein said pressure inthe second chamber is provided by the additional steps: providing apositive pressure from a pressure source; forwarding at least part ofsaid pressure from the pressure source to a pressure accumulation tankconnected to said source through in a non-returnable way; and forwardingat least part of said pressure from the pressure accumulation tank tothe second chamber through a mechanical pressure regulator arrangedbetween said pressure accumulation tank and said second chamber.
 30. Aself-contained portable apparatus for administration of a drug solution,said apparatus comprising: a housing having an enclosure for receiving aflexible pouch; an inflatable bladder, said inflatable bladder beingwrapped around the flexible pouch containing the drug solution in apressure-transmitting relation within said enclosure; a pressurizationsystem for providing a constant and controllable gas pressure to saidinflatable bladder, wherein a controllable pressure is obtained in saidpouch for a controllable delivery of the drug solution, wherein saidpressurization system is integrated on or within the housing, andcomprises: a pressure accumulation tank connected to the inflatablebladder, arranged to provide a positive pressure reservoir; amechanical, hand-operated pump, comprising an air compression cup whichis slideably arranged over the pressure accumulation tank.
 31. Aself-contained portable apparatus for administration of a drug solution,said apparatus comprising: a housing having an enclosure for receiving aflexible pouch; an inflatable bladder, said inflatable bladder beingwrapped around the flexible pouch containing the drug solution withinsaid enclosure; a pressure accumulation tank connected to the inflatablebladder and being integrated on or within the housing; and a mechanical,hand-operated pump, comprising an air compression cup which is slideablyarranged over the pressure accumulation tank.